1. Field of the Invention
The present invention relates to ink jet printers, and, more particularly, to a nozzle assembly for an ink jet printer.
2. Description of the Related Art
An ink jet printer emits droplets of ink through the nozzles of a printhead and onto a print medium. The nozzles are formed in a nozzle plate that is laminated onto a heater chip to form a nozzle assembly. Resistive heaters within the heater chip heat the ink until the ink is vaporized and is thereby emitted through the nozzles.
Creation of a nozzle plate typically occurs in a process separate from the creation of the heater chip. The nozzle plate must then be aligned and adhered to the heater chip. The tolerances that build up during the fabrication, alignment and adhering of the nozzle plate limit the size and quantity of heaters and nozzles. Creating a nozzle plate on the heater chip itself improves the accuracy of the alignment between the nozzles and heaters to the level of the accuracy of the align/expose equipment.
It is known to create a structural member for ink flow channels and nozzles with two layers of imageable material. An ink cavity is formed in the first layer and nozzle holes are formed in the second layer. In a roof-shooter style ink jet printhead, the width of the ink cavity created in the first layer can be up to 500 microns. Because of the relatively large width of this span and the relative thinness of the second layer typically used, the second layer has a tendency to collapse into the ink cavity, thereby compromising the function of the nozzle plate.
What is needed in the art is a nozzle plate in which a relatively thin first layer of imageable material, which contains nozzle holes, is supported by a second layer that contains an ink cavity, such that the first layer does not collapse into the ink cavity of the second layer.
The present invention provides a nozzle plate formed from an imageable material sandwiched around a structural support mechanism.
The invention comprises, in one form thereof, an ink jet nozzle assembly including a heater substrate and a nozzle plate. The nozzle plate includes a first resist layer having a first side laminated onto the heater substrate. The first resist layer includes an ink cavity and at least one heater chamber in fluid communication with the ink cavity. A support layer has a first side and a second side. The first side of the support layer is in contact with a second side of the first resist layer such that the support layer at least partially covers the ink cavity. A second resist layer has a side in contact with each of the second side of the first resist layer and the second side of the support layer. The second resist layer is supported by the support layer such that the second resist layer is retained substantially outside of the ink cavity. The second resist layer includes at least one nozzle hole. Each nozzle hole is substantially aligned with a corresponding heater chamber.
An advantage of the present invention is that a relatively thin photoresist layer of the nozzle plate is able to successfully span the ink cavity without collapsing therein.
Another advantage is that the ink cavity can be easily cleaned out, resulting in fast throughput, less chemical usage, and tighter control on the ink cavity side wall definition.